1. Field of the Invention
The present invention relates to a novel process for producing 3,5-dichloro-.alpha.-methylstyrene from 1-bromo-3,5-dichlorobenzene.
3,5-Dichloro-.alpha.-methylstyrene is useful intermediate for various agricultural chemicals, medicines and dyes and also useful monomer for rubbers, plastics and resins.
2. Description of the Prior Arts
An industrial process for producing 3,5-dichloro-.alpha.-methylstyrene has not been developed.
The inventors have studied on various processes for finding an industrially advantageous process for producing 3,5-dichloro-.alpha.-methylstyrene. As the results, the inventors have found that bromine atom in 1-bromo-3,5-dichlorobenzene which could be economically produced in a mass production, has significantly higher reactivity to magnesium than that of chlorine atom and accordingly, the object compound of 3,5-dichloro-.alpha.-methylstyrene can be effectively produced in an industrial scale from 1-bromo-3,5-dichlorobenzene obtained in a mass production.
It has been known that 3,5-dichloro-.alpha.-methylstyrene can be produced by reacting thionyl chloride with 3,5-dichlorobenzoic acid to obtain 3,5-dichlorobenzoyl chloride and then reacting methanol with 3,5-dichlorobenzoyl chloride to obtain methyl-3,5-dichlorobenzoate and reacting methylmagnesium chloride with methyl-3,5-dichlorobenzoate in ether and then, hydrolyzing the product with a diluted hydrochloric acid and dehydrating the product over sodium bisulfate, in for example, Journal of the American Chemical Society 73 January 1951, page 455-456. However, this process is not advantageous as an industrial process because many reaction steps are needed for producing methyl3,5-dichlorobenzoate and a complicated reaction step is included in these steps for producing the starting material and the hydrolysis and the dehydration should be separately carried out.